Question

When a current loop is placed in a uniform magnetic field, then it is possible that it experience ($\overrightarrow{F}_R$ = resultant magnetic force, $\overrightarrow{\tau}$ = net magnetic torque)

• A. $\overrightarrow{F}_R$ = 0 and $\overrightarrow{\tau}$ = 0
• B. $\overrightarrow{F}_R$ = 0 and $\overrightarrow{\tau}$ $\neq$ 0
• C. $\overrightarrow{F}_R$ $\neq$ 0 and $\overrightarrow{\tau}$ = 0
• D. $\overrightarrow{F}_R$ $\neq$ 0 and $\overrightarrow{\tau}$ $\neq$ 0

Answer 1

Answer: (A), (B)

$\overrightarrow{F}_R = 0$ and $\overrightarrow{\tau} = 0$, $\overrightarrow{F}_R = 0$ and $\overrightarrow{\tau} \neq 0

Answer 2

A current loop in a uniform magnetic field always experiences zero net force because the vector sum of infinitesimal displacement elements over a closed loop is zero. The net torque on the loop depends on its orientation relative to the magnetic field. If the magnetic moment of the loop is aligned (parallel or anti-parallel) with the magnetic field, the torque is zero. Otherwise, the torque is non-zero. Thus, two possibilities exist: zero force and zero torque, or zero force and non-zero torque.